Spark-plug



A. F. AND v. ofcoLLlNs.

I SPARK PLUG.

APPLICATION FILED JUNE 1 7, 1.919.

Patent-ea Dec. 27, 1921.

ARCHIE FREDRICK COLLINS AND 'VIRGIL DEWEY COLLINS, 0F CONGERS, NEW' YORK.

SPARK-PLUG.

Specification. of Letters Patent. Patented Dec. 27, 1921.

Application led. .Tune 17, 1919. Serial No. 304,845.

To all whom t may concern.'

Be it known that we, ARGHIE FREDERICK COLLINS and VIRGIL D. COLLINS, citizens of the United States, residing at Congers, in the county of Rockland and State of New York, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification.

This invention relates to spark plugs for gas iengines, the object thereof being to provide an improved spark plug in which the terminal electrodes or, wires may not only be adjusted one relatively to the other whereby the lspark gap may be varied and setto suit varyin conditions not only with precision but suc setting mathematically and accurately measured without the use of any independent means for this purpose and this when desired without the removal of the plug from the engine.

A further object of the invention is the provision of an improved spark plu having formed as a art thereof means or accurately measurlng the spark gap during the setting thereof and which means is also,

e'ective to vary the spark gap as occasion re 'uires further objectof the invention is4 the provision of an improved spark plug having embodied therein a micrometer vfor measuring the raccuracy of the spark gap and also including means for accurately correcting such micrometer.

A' further object of the invention is the provision of an improved Spark plu .having embodied therein not only means or accurately varying the spark gap as the conditions of the engine may require without the removal of the plug from the en ine, but which means may also be utilized or deter mining whether the spark gap is varied durin the running of the engine. A

rther object of the invention is the Y provision of an Improved spark plug so constructed that it may be readily taken apart for cleaning and quickly assembled, but which is so constructed that it affords increased protection against gas leakage.

A further object of the invention is the 'provision of an improved spark plug having the advantages herein set forth, Whlch however, is simple in construction, comparativel inexpensive to manufacture and very dura le and eficient in use.

A further object of the invention is the provision of an improved spark plug having an improved form ofinsulator.

A further object of the invention is the provision of an improved spark plug having improved means for preventing the breakage ofthe insulator. on the slippage of the wrench.

In the drawings accompanying and forming a part of this specification, Figure l is a side view of one form of this improvedl spark plug; Fig. 2 is a vertical sectional view thereof; Fig. 3 is a partly vertically sectional view showing one way in which the terminal electrodes may be adjusted; Fig. 4 illustrates a somewhat different form of the measuring and adjusting means; Fig. 5 illustrates a still differenty form of the measuring and adjusting means; Fig. 6 is a verticalv sectional view of the upper part of the plug shown in Figs. 1 and 2; and Fi 7 is a cross sectional view of Fig. 2.

imilar characters of reference indicate corresponding parts in the several gures'of the drawings.

As is well known to those versed in the art of automobile ignition, there are certain exacting conditions which must be met and therefore the spark plug lmust be designed and constructed in order to meet such conditions; for instance the spark gap length must be accurately varied to the thousandth of an inch as the compression is increased or decreased or as the speed of the engine increases or decreases, or as the richness of the fuel charge increases or decreases, or as the current strength and the electromotive force increases or decreases, or as the frequency of the oscillatory discharge increases or decreases.

Moreover the plug must be so constructed as to revent any leakage of the compressed fuel cih accessible for cleaning.

'Further the plug must be so insulated as to prevent any leakage of the high tension vcurrent or short circuiting in the plug.

In addition, the electrodes must be so constructed or protected or both that they will not become heated to incandescence and preignite the fuel charge in .hi h speed, high compression engines of smal firing chamber volume. y

And nally, it is also necessary that the insulating material projecting above the plug shell shall be so `pmtetltld @S t0 prevent` arged through it and must be readily cylinder, yet so far as weare aware, no`

accidental breakage by theslipping of the wrench when screwing the "plug into the cylinder or unscrewingthe same. The present improvement provides an efficient spark plug which will meet the foregoing conditions.

F or every makev of engine built, for the diderent compressions` that are employed, and for the varying sizes and proportions of the cylinders, and for the specific type of ignition system used, there is a critical spark gap length which is necessary. ln

other words, there is a spark gap length that is the most efficient. v

As every automobile owner is aware, the ordinary plug in common use of whatever form or' make must be taken out of the cylinder head and whatever adjustment that is made by the maker of the engine or byl the owner thereof isusually guess work and must be made with a pair of pliers, and if any attempt is made to even approximately make the adjustment accurate a thickness gage must be used which is a method comparable to that of'measuring the thickness of a sheet of paper with a carpenters rule. @bviously this is a very laborious and impractical way oi"- obtaining an accuratel adjustment of a spark gap that must be limited to the variation of not' more than .010 of an inch, v1. e. between .020 to .030 of an inch.

While we are aware of' the fact that patents have been granted for ,spark plugs in which the spark gap can be varied or adjusted without removing the plug from the patent has ever been issued in which means are provided for measuring the spark gap length. ln order words, while the prior art discloses patents showing the plu fitted with an indicator by means of which the spark gap may be rough-lygaged, they are of no -practical value since the spark gap cannot be measured by such a construction. of indicator as herein referred'to.

lin the present improvement the spark plugv has embodied therein a micrometer, by means or which the spark gap length can, be measured to the .001 of an inch 'and not onlythis7 butthe terminals are' adjustable one relatively to the other whereb the spark gap length is variable and thiswlthout even removing the plu from the cylinder.

'lhis improve spark .plug in` the various forms thereof shown, comprises a chamber-ed shell 2, having an exteriorly threaded lower end 3 for insertion vinto the engine. lio-- cated within this shell and fitting on to a shoulder thereof is a suitable gasket 4. The shell carries suitable' insulating material 5 shown in the form of a porcelain insulator, which is secured within the shell by means of a nut-or sleeve 6, suitable gaskets 7 and 8 bein located between lthe upper end of the. she l and a shouldered portion 9 of the porcelain and between a similarly shoul-v dered portion 13 of the porcelain and the -inturned edge le of the sleeve thereby to provide gas-tight joints. lhe nut or sleeve is threaded on to the upper end ot the shell in a manner which will be readily understood. rlhe porcelain shown is ofthe chambered or petticoat form and carries within the same thecentral electrode or terminal wire 15, the other terminal wire 16 being carried by the shell in the usuall manner. rlhe central terminal wire is provided with threads 17, fifty threads to the inch, and these threads mesh with a threaded stationary sleeve 18 set into or threaded into the insulator with a gas-tight `joint at its lower end obtained by means oit a suitable gasket. 19. Mounted on the upper end of this trode rigidly carries 'a uted `micrometer sleeve 23 which is adapted on the rotation thereof to slide up and down in the thimble t just'described, which is chambered as at 25 for this purpose. lo the thimble 20 in the forms shown in Figs. 1, 2 and 6 is secured a spring pointer or locking latch 26 shown in these views as a pivoted latch, the lower end of which is in engagement with a spring 27 seated in a recess in the thimble and the upper end of which latch is thus pressed into engagement with the grooves or flutes in the micrometer sleeve 23. ln the form shown in Fig. 11 the pointer or'latch is in the form of a leaf sprin 27 riveted or otherwise secured tothe thim le` 20 and adapted to engage flutes or grooves 28 .of the micrometer sleeve 29., 'whilein the1 form shown "in rio Fig'. 5 the pointer or latch is also shownas a lleaf spring seeured to ailmurlednutl formed as apart ot a rotatable 'sleeve 32. ln this last it'orm the micrometer grooves or recesses 33 are formed at the top of the thimble 20. lin all forms it will be understood that the sleeve 23 or 29 or 32 is of course rigidly secured to the 'terminal electrode 15 so that the electrode will rotate with such sleeve. -ln any ot the forms shown, the latch will readil slip into and out of the dutings, of which there are twenty on the micrometer sleeve, when the sleeve is rotated in the proper manner. ln the form shown in Fi s. 1, 2 and 6, the terminal post 34 and nut or the connection of the conduit wireis shown atl the side of the thimble, but thisl could be otherwise located if desired.

When it is `desired to set the spark gap to. a certain micrometric length, it is merely ist ree

. and as this sleeve is securely fixed to thev central electrode, the latter will rotate with necessary to turn the sleeve'23 or 29 or 32 by means of its knurled or grooved nut,

the sleeve until the points of the electrodes just touch each other.l vWhen -they are'- in'v this position the lockin latch or spring pointer will engage with t e 0 or zeroiuting of the micrometer scale on the sleeve.

As there are fifty threads to the inchl on the. central electrode, it is obvious that for f every twentieth ofa' turn of the micrometer building up sleeve the length of the spark gap will be varied by one-thousandth of an inch, so that every time the'micrometer sleeve isgiven a' twentieth of a turn, the spring ointerv or locking latch slips from its positlon in one luting until it engages into'th'e'next, and hence as stated, the spark gap length is varied by one-thousandth of an; inch. This micrometric measurement of the variation of the spark gap length is furtherfacihtated' by the scale numbers stamped on or in proximity to the fluted scale on the micrometer The spark gap length is frequently lengthcned also by the heat burning off the ends of the electrodes or by the warping thereof. Consequently the present improvement will tend to show when the piston rings permit the lubricating oil to .leak past them into the combustion chamber or when too rich a fuel mixture is being used, orwhen the electrodes are not being properly cooled and thus edect the terminal points. For-instance, to ascertain whether the spark gapis too short or too long due toany of the conditions hereinbefore referred to, it is only necessary to -bring the electrodes together as far as is possible by rotating the micrometer sleeve in the proper direction. lf they are in proper condition, then the lock spring orv will engage with the flute marked 0, that is, 'if the electrodes are of normal length or in proper condition but if the length of the electrodes has been altered in any Way during the running of the engine, the lock spring will not engage with the zero iiuting of the scale, but with pointer Zero or a fluting' to one side or the other thereof,

and since each flirting represents .001 of an inch it can be readily and exactly deterhas been shortened'due to the mined how much the b the building up ort e burning -oif of the e ectrodes. In this condition onf course the micrometer, if manipulated will not give the true spark gap .length accurately, and hencethis gap cannot now be leffectively-adjusted,

gdlap has been altered I but by means' of the present improvement the calibration of the micrometer can be readily made, so that thefspark plug gap can be again accuratelyadjusted. This cahbration is etfected'by means of the rotatable thimble 20 hereinbefore described,I which can be rotated in either direction, that is, f I clockwlse or counter-clockwise, asthe case may be,-until the spring latch again engages with the zero fiuting of the micrometer sleeve, and when -so adjusted, in'other words, when the micrometer has been calibrated in the manner described to accuracy then itis again ready for use.

In other words in order to calibrate, z'. e. to correct or rectify the graduations of the micrometer or measuring instrumentality for ascertaining withV mathematical accuracy the length of spark gap, it is merely necessary to rotate the sleeve 23, 29 or 32, f v

as the case maybe until the electrode 15 contacts with the electrode 16. When, therefore, as illustrated in Fig. 5, the pointer 30 engages the iiuting as, for instance,'at grad-- uation No. 3, it .will be necessary to reposition the thimble 20V so as to place the graduation reading zero of the thimble 20 opposite this fluting 3wheren the pointer or mdicator 30 now rests in its newly adjusted position. This is necessary in order to adjust thereafter the spark'gap between the electrodes by measuring the same Vfrom a zero graduation on the thimble. As herein-a before set forth, this calibration of thel micrometer or, in other words, the rectiing ofthe graduations thereof is'obtaine by -rotatingthe thimble 20 so that the zero graduation thereof will correspond tothe new position of the pointer -30 on the iiuting with electrode 15 at the same time vin contact with electrode 16. f

.-\Having accomplished this correction `or calibration of the 'measuring' means, the sleeve 23, 29 o r 32 may then be rotated to adjust anew the spark gap the proper amount..

lt will of course be'obvious` that thefvarious details maybe more or less departed. from without departing from the spirit or scope of the present improvement, and that instead of adjusting the central'electrode' lengthwise the .central electrode 15 may be rotated, for instance asin Fig. 3,- te' carry it toward and from its companion uelectrode or in place 4ci the pivoted locking latch shown in Figs. 1 and 2 a leaf spring i may be used, as shown in Figs. e and 5, an thatinstead of carrying the iiutings on the micrometer sleeve as shown'4 in Figs. 1, 2 and 6, they may be carried on the nut formed as 'a part of the sleeve 20 as shown in Fig. a or in Fig. -5, allof which forms of the device however, embody the micrometer principle in combination with a spark plug having an adjustable spark gap.

T here are two forms of spark plugs well known upon the market,-one comprising the assembled plug in which the parts may be readily separated for cleaning, and the other the pressed plug. rlhe present construction combines the best qualities of both types in that it offers protection against gas leakage andl yet the parts of the plug may be readily sepa-rated and quickly assembled, and therefore the plug need not be thrown away when it becomes sooted.

ln the present improvement, the sleeve 18 carrying the central electrode is pressed into the insulator, which makes it gas-tight, and this insulator is also made gas-tight in the plug shell 2 by means of the removable hexagonal ring nut or sleeve 6, which enables the plug .to be readily taken apart and cleaned.

lt is well known to those versed in high frequency and high potential electricity that the best shape for an insulator is one having a corrugated surface; this is because the corrugations provide a larger surface per unit of area than a liat surface and hence it offers a greater resistance to the'high tension currents, which may leak through, and' which tend to travel on the surface.

llt is further well known that spark plug insulators of the petticoat type provide a better protection against the leakage of the high tension currents when they become soot/ed by reasony of the additional surface area they offer. From the construction of the insulator shown in the present improvement, it will be observed that the corrugated petticoat type shown provides nearlyonethird more surface area and hence resistance than any others of which we are aware, since both opposing walls 35 and 36 of the charnf bored porcelain around the central electrode are corrugated as well as that portion thereof as 3'? which projects beyond the metalbody portions of the plug,

It is also `known to designers and manufacturers of high compression, high speed engines having small combustion chambers, that the ordinary petticoat insulator is undesirable for its leaves the central electrode unprotected and the intense heat developed causes the electrode to become incandescent, when of` course pre-ignition occurs, and therefore these designers and manufacturers recommend solid insulators in those of the petticoat type. ow, as solid insulators provide but smallsurface resistance to short circuiting dueto-soot, it will he operative position.

reference to Leonesa readily seen that the present improved insulator which is a combination of the solid and petticoat type, is a great improvement since the hexagonal ring nut or sleeve 6 takes.

the place of the small internal bushing usually found in the ordinary plug, and as this ring nut is above and extends outwardly beyond the shell 2 whichis provided with-the usual wrench receiving surface, it follows that when the wrench is appliedto the shell the wrench cannot slip od and` u and so strike the insulator and break it. j hus the present improvement provides a long life plug.

We claim as our invention:

l. A spark plug having a pair of electrodes, one adjustable relatively to the other thereby'to vary the spark gap, said plug embodying means for -ad'usting said electrode, means for accura y measuring the spark gap, and means for correcting the settin of such measuring means.

2. spark plug havin'g a pair of electrodes, one adjustable relatively to the other thereby to vary the spark gap, said plug -1 embodying means for adjusting said electrode, means for accurately adjusting the spark gap-, and means for. calibrating said measuring means while the plug is in its ,3. A. spark plug having ay pair1 ofv electrodes, oneadjustable relatively to the other thereby to vary the spark gap, said plug embodying means for adjusting said electrede, a micrometer for accurately measuring the spark gap, and means for calibrating iin said micrometer while the plug is in its operative position.

4. Av ark plug having a pair of elec-l trodes, one adjustable lengthwise relatively to the other thereby to vary the spark gap, said plug' embodying means lfor adjusting said adjustable electrode lengthwise, meansl for accurately measuring the spark gap, and means 'for calibrating such measuring means while the plug is in its operative position.

5. A spark plug having a pair of electrodes including a centrally located one adjustable relatively to its Icompanion electrode thereby to vary the spark gap, said plug embodying means for adjusting said electrode, means for accurately measuring the spark gap, and means for correcting the' setting 'of such measuring means 'while the plug is in its operative position.

6. A spark plug having a pair 'of lelecf trodes including a centrally located one adjustable relatively to its companion electrode thereby' to vary the spark' gap, micrometer means for adjusting said central electrode and accurately measuring the spark gap, and means for calibrating said micrometer while the plug is in its operative position.

7. A spark plug having a pair of electrodes, one comprising a centrally-located electrode adjustable relatively to its companion electrode thereby tto vary the spark gap, means for adjusting and accurately measuring such p without remloving the plug from the cy 'dei' and including a micrometer measuring instrumentality, and means for calibrating` it.

8. A spark plug having a air of electrodes, one comprising a mova le electrode shiftable toward and from its companion electrode, measuringand calibrating means comprising a pair of rotary elements, one adapted to control the movement of said movable electrode and the other movable independently thereof whereby the spark gap may be accurately measured and said measuring means may be rectified.

9. A spark plug having a pair of electrodes, one comprising a centrally located adjustable electrode having a predetermined number of threads to the inch, a rotary sleeve rigidly secured to said adjustable electrode and having a predetermined number of graduations whereb the spark gap may be varied and measure and means Jfor calibrating said measuring instrumentality while the plug is'in an operative position.

10. A spark plug having a pair of electrodes, one comprising a centrally located adjustable electrode having a predetermined number of threads to the inch, a rotary sleeve l secured to said adjustable electrode and ef- 1 and having a fective to rotate the same and having a predetermined number of graduations whereby the spark ga may be varied and measured,- means for ca ibrating said measur' instrumentality, and means for holding said sleeve in its adjusted position.

11. A spark plu g. having a pair of velectrodes, one comprising a centrally located adjustable electrode having a predetermined number of threads to the inch, a rotary sleeve rigidly secured tov said adjustable electrode predetermined number of graduations whereby the spark gap may be varied and measured, means for Calibrating said measuring instrumentality when the plug is in the cylinder, and means for holding said sleeve in its adjusted position and comprising a spring actuated latch, said sleeve having its graduations in the form ot flutes adapted to coperatie with said latch.

12. A spark plug having-a pair ot electrodes, one comprising a centrally located adjustable electrode having a predetermined number of threads'to the inch, a micrometer sleeve carried by said adjustable electrode and effective to rotate the central electrode thereby to vary the spark gap, means for holding said micrometer sleeve in its adjusted position and comprising a spring actuated latch, the graduations on the micrometer sleeve comprisinggrooves adapted to coperate. with said latch, and means for Calibrating said micrometer sleeve when the plug is in the cylinder.

13. A spark plughaving a. pairof elecplugl from the cylinder and comprising a rotary sleeve with which said latch coperates.

14. A spark plug having a pair of electrodes, one adjustable relatively to the other thereby to vary the spark gap, said plug embodying a micrometer for accurately measuring the spark gap length and comprisingA a graduated sleeve secured to and rotatable with said adjustable electrode whose displacement is such that the ratio of the angular movement of the electrode to the length to which` the spark gap is varied may be accurately determined, and means carried b the plug for accurately rectifying the gra I uations of said micrometer.'

15. A spark plug having a pair of electrodes, one comprising a centrally adjustable electrode, a micrometer for accurately measuring the spark gap length and consisting of a sleeve rigidly secured tosaid adjustable electrode and having equi-distant utes around its circumference, said electrode having a predetermined number of threads to the inch and coperating with a threaded stationary sleeve carried by the plug, a

'spring pointer adapted to engage the flutes of the sleeve, and a rotary thmble carrying said spring pointer.

16. A spark plug havinga pair of elec-l trodes, one adjustable relatively to the other thereby to vary the spark gap, said adjustable electrode having a predetermined number of threads to the inch, an interiorly threaded member co erating with saidl adjustable electrode an having an exteriorly threaded end, a threaded member coperating with 'said 'threaded end and rotatable relatively thereto, a micrometer sleeve rigidly secured te said adjustable electrode, and. indicating mea-ns carried by said last ias'- l Leeneee threaded member and ooperating with said micrometer sleeve whereby the spark gap may not only be varied and measured bur` the micrometer calibrated.

17. A spark plug having a pair of elec trodes, one adjustable relatively to the other thereby to vary the spark gap, micrometer means carried by said plug for accurately measuring the spark gap., and means also earrieol by the plug for Calibrating said -micrometer means.

18. A spark plug having ealibralzing means operable While -flie plug is in its eective position.

19. A ,spark plug having measuring M5 means, and means for Calibrating said measuring means in an operative as Well as an inoperative position of said plug.

Signed` at Congers county of Rockland and State of New ork, this 11th day olf 2@ June, 1919. l

ARCHllE FREDERICK ClLlLlNS. -I i VllRGlllL lDlE-'WEY CLLINS. 

